Hydrogen generation assemblies

ABSTRACT

Hydrogen generation assemblies and methods of generating hydrogen are disclosed. In some embodiments, the method may include receiving a feed stream in a fuel processing assembly of the hydrogen generation assembly; and generating a product hydrogen stream in the fuel processing assembly from the received feed stream. Generating a product hydrogen stream may, in some embodiments, include generating an output stream in a hydrogen generating region from the received feed stream, and generating the product hydrogen stream in a purification region from the output stream. The method may additionally include receiving the generated product hydrogen stream in a buffer tank of the hydrogen generation assembly; and detecting pressure in the buffer tank via a tank sensor assembly. The method may further include stopping generation of the product hydrogen stream in the fuel processing assembly when the detected pressure in the buffer tank is above a predetermined maximum pressure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/483,265, which was filed Apr. 10, 2017 and entitled “HydrogenGeneration Assemblies and Hydrogen Purification Devices,” which is acontinuation application of U.S. patent application Ser. No. 14/931,585,filed Nov. 3, 2015 and entitled “Hydrogen Generation Assemblies andHydrogen Purification Devices,” which issued as U.S. Pat. No. 9,616,389on Apr. 11, 2017, which is a divisional application of U.S. patentapplication Ser. No. 13/829,766, filed Mar. 14, 2013 and entitled“Hydrogen Generation Assemblies and Hydrogen Purification Devices,”which issued as U.S. Pat. No. 9,187,324 on Nov. 17, 2015, which is acontinuation-in-part application of U.S. patent application Ser. No.13/600,096, filed Aug. 30, 2012 and entitled “Hydrogen GenerationAssemblies.” The complete disclosures of the above applications arehereby incorporated by reference for all purposes.

BACKGROUND OF THE DISCLOSURE

A hydrogen generation assembly is an assembly that converts one or morefeedstocks into a product stream containing hydrogen gas as a majoritycomponent. The feedstocks may include a carbon-containing feedstock and,in some embodiments, also may include water. The feedstocks aredelivered to a hydrogen-producing region of the hydrogen generationassembly from a feedstock delivery system, typically with the feedstocksbeing delivered under pressure and at elevated temperatures. Thehydrogen-producing region is often associated with a temperaturemodulating assembly, such as a heating assembly or cooling assembly,which consumes one or more fuel streams to maintain thehydrogen-producing region within a suitable temperature range foreffectively producing hydrogen gas. The hydrogen generation assembly maygenerate hydrogen gas via any suitable mechanism(s), such as steamreforming, autothermal reforming, pyrolysis, and/or catalytic partialoxidation.

The generated or produced hydrogen gas may, however, have impurities.That gas may be referred to as a mixed gas stream that contains hydrogengas and other gases. Prior to using the mixed gas stream, it must bepurified, such as to remove at least a portion of the other gases. Thehydrogen generation assembly may therefore include a hydrogenpurification device for increasing the hydrogen purity of the mixed gasstream. The hydrogen purification device may include at least onehydrogen-selective membrane to separate the mixed gas stream into aproduct stream and a byproduct stream. The product stream contains agreater concentration of hydrogen gas and/or a reduced concentration ofone or more of the other gases from the mixed gas stream. Hydrogenpurification using one or more hydrogen-selective membranes is apressure driven separation process in which the one or morehydrogen-selective membranes are contained in a pressure vessel. Themixed gas stream contacts the mixed gas surface of the membrane(s), andthe product stream is formed from at least a portion of the mixed gasstream that permeates through the membrane(s). The pressure vessel istypically sealed to prevent gases from entering or leaving the pressurevessel except through defined inlet and outlet ports or conduits.

The product stream may be used in a variety of applications. One suchapplication is energy production, such as in electrochemical fuel cells.An electrochemical fuel cell is a device that converts fuel and anoxidant to electricity, a reaction product, and heat. For example, fuelcells may convert hydrogen and oxygen into water and electricity. Inthose fuel cells, the hydrogen is the fuel, the oxygen is the oxidant,and the water is a reaction product. Fuel cell stacks include aplurality of fuel cells and may be utilized with a hydrogen generationassembly to provide an energy production assembly.

Examples of hydrogen generation assemblies, hydrogen processingassemblies, and/or components of those assemblies are described in U.S.Pat. Nos. 5,861,137; 6,319,306; 6,494,937; 6,562,111; 7,063,047;7,306,868; 7,470,293; 7,601,302; 7,632,322; U.S. Patent ApplicationPublication Nos. 2006/0090397; 2006/0272212; 2007/0266631; 2007/0274904;2008/0085434; 2008/0138678; 2008/0230039;

2010/0064887; and U.S. patent application Ser. No. 13/178,098. Thecomplete disclosures of the above patents and patent applicationpublications are hereby incorporated by reference for all purposes.

SUMMARY OF THE DISCLOSURE

Some embodiments may provide a hydrogen generation assembly. In someembodiments, the hydrogen generation assembly may include a fuelprocessing assembly configured to receive a feed stream and produce aproduct hydrogen stream from the feed stream. The hydrogen generationassembly may additionally include a feed assembly configured to deliverthe feed stream to the fuel processing assembly. The feed assembly mayinclude a feed tank configured to contain feedstock for the feed stream,and a feed conduit fluidly connecting the feed tank and the fuelprocessing assembly. The feed assembly may additionally include a pumpconfigured to deliver the feed stream at a plurality of flowrates to thefuel processing assembly via the feed conduit. The hydrogen generationassembly may further include a control system. The control system mayinclude a feed sensor assembly configured to detect pressure in the feedconduit downstream from the pump. The control system may additionallyinclude a pump controller configured to select a flowrate from theplurality of flowrates based on the detected pressure in the feedconduit, and to operate the pump at the selected flowrate.

In some embodiments, the hydrogen generation assembly may include a fuelprocessing assembly configured to receive a feed stream and produce aproduct hydrogen stream from the feed stream. The hydrogen generationassembly may additionally include a pressurized gas assembly configuredto receive at least one container of pressurized gas that is configuredto purge the fuel processing assembly. The hydrogen generation assemblymay further include a purge conduit configured to fluidly connect thepressurized gas assembly and the fuel processing assembly. The hydrogengeneration assembly may additionally include a purge valve assemblyconfigured to allow the at least one pressurized gas to flow through thepurge conduit from the pressurized gas assembly to the fuel processingassembly when power to the fuel processing assembly is interrupted.

In some embodiments, the hydrogen generation assembly may include a fuelprocessing assembly configured to receive a feed stream and to beoperable among a plurality of modes, including a run mode in which thefuel processing assembly produces a product hydrogen stream from thefeed stream, and a standby mode in which the fuel processing assemblydoes not produce the product hydrogen stream from the feed stream. Thehydrogen generation assembly may additionally include a buffer tankconfigured to contain the product hydrogen stream, and a product conduitfluidly connecting the fuel processing assembly and the buffer tank. Thehydrogen generation assembly may further include a tank sensor assemblyconfigured to detect pressure in the buffer tank, and a control assemblyconfigured to operate the fuel processing assembly between the run andstandby modes based, at least in part, on the detected pressure in thebuffer tank.

Some embodiments may provide a steam reforming hydrogen generationassembly configured to receive at least one feed stream and generate areformate stream containing hydrogen gas as a majority component andother gases. In some embodiments, the steam reforming hydrogengeneration assembly may include an enclosure having an exhaust port, anda hydrogen-producing region contained within the enclosure andconfigured to produce, via a steam reforming reaction, the reformatestream from the at least one feed stream. The steam reforming hydrogengeneration assembly may additionally include a reformer sensor assemblyconfigured to detect temperature in the hydrogen-producing region. Thesteam reforming hydrogen generation assembly may further include aheating assembly configured to receive at least one air stream and atleast one fuel stream and to combust the at least one fuel stream withina combustion region contained within the enclosure producing a heatedexhaust stream for heating at least the hydrogen-producing region to atleast a minimum hydrogen-producing temperature. The steam reforminghydrogen generation assembly may additionally include a damper moveablyconnected to the exhaust port and configured to move among a pluralityof positions including a fully open position in which the damper allowsthe heated exhaust stream to flow through the exhaust port, a closedposition in which the damper prevents the heated exhaust stream fromflowing through the exhaust port, and a plurality of intermediate openpositions between the fully open and closed positions. The steamreforming hydrogen generation assembly may further include a dampercontroller configured to move the damper between the fully open andclosed positions based, at least in part, on the detected temperature inthe hydrogen-producing region.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an example of a hydrogen generationassembly.

FIG. 2 is a schematic view of another example of a hydrogen generationassembly.

FIG. 3 is a partial schematic view of an additional example of ahydrogen generation assembly.

FIG. 4 is a schematic view of an example of a control assembly.

FIG. 5 is a graph showing an example of the control assembly of FIG. 4receiving a detection signal and conditioning the detection signal togenerate a conditioned signal.

FIG. 6 is a partial schematic view of a further example of a hydrogengeneration assembly.

FIG. 7 is an example of a purge assembly of a hydrogen generationassembly.

FIG. 8 is another example of a purge assembly of a hydrogen generationassembly.

FIG. 9 is a partial schematic view of an additional example of ahydrogen generation assembly.

FIGS. 10-12 are partial schematic views of the hydrogen generationassembly of FIG. 9 showing another example of a damper and examples ofpositions for that damper.

FIG. 13 is a partial schematic view of a further example of a hydrogengeneration assembly.

FIG. 14 is a partial schematic view of another example of a hydrogengeneration assembly.

FIG. 15 is a partial schematic view of the hydrogen generation assemblyof FIG. 14 showing a three-way valve in a flow position.

FIG. 16 is a partial schematic view of the hydrogen generation assemblyof FIG. 14 showing the three-way valve of FIG. 15 in a vent position.

FIG. 17 is a partial schematic view of a further example of a hydrogengeneration assembly.

FIG. 18 is a partial schematic view of the hydrogen generation assemblyof FIG. 17 showing a first valve in an open position and a second valvein a closed position.

FIG. 19 is a partial schematic view of the hydrogen generation assemblyof FIG. 17 showing the first valve of FIG. 18 in a closed position andthe second valve of FIG. 18 in an open position.

DETAILED DESCRIPTION OF THE DISCLOSURE

FIG. 1 shows an example of a hydrogen generation assembly 20. Unlessspecifically excluded hydrogen generation assembly may include one ormore components of other hydrogen generation assemblies described inthis disclosure. The hydrogen generation assembly may include anysuitable structure configured to generate a product hydrogen stream 21.For example, the hydrogen generation assembly may include a feedstockdelivery system 22 and a fuel processing assembly 24. The feedstockdelivery system may include any suitable structure configured toselectively deliver at least one feed stream 26 to the fuel processingassembly.

In some embodiments, feedstock delivery system 22 may additionallyinclude any suitable structure configured to selectively deliver atleast one fuel stream 28 to a burner or other heating assembly of fuelprocessing assembly 24. In some embodiments, feed stream 26 and fuelstream 28 may be the same stream delivered to different parts of thefuel processing assembly. The feedstock delivery system may include anysuitable delivery mechanisms, such as a positive displacement or othersuitable pump or mechanism for propelling fluid streams. In someembodiments, feedstock delivery system may be configured to deliver feedstream(s) 26 and/or fuel stream(s) 28 without requiring the use of pumpsand/or other electrically powered fluid-delivery mechanisms. Examples ofsuitable feedstock delivery systems that may be used with hydrogengeneration assembly 20 include the feedstock delivery systems describedin U.S. Pat. Nos. 7,470,293 and 7,601,302, and U.S. Patent ApplicationPublication No. 2006/0090397. The complete disclosures of the abovepatents and patent application are hereby incorporated by reference forall purposes.

Feed stream 26 may include at least one hydrogen-production fluid 30,which may include one or more fluids that may be utilized as reactantsto produce product hydrogen stream 21. For example, thehydrogen-production fluid may include a carbon-containing feedstock,such as at least one hydrocarbon and/or alcohol. Examples of suitablehydrocarbons include methane, propane, natural gas, diesel, kerosene,gasoline, etc. Examples of suitable alcohols include methanol, ethanol,polyols (such as ethylene glycol and propylene glycol), etc.Additionally, hydrogen-production fluid 30 may include water, such aswhen fuel processing assembly generates the product hydrogen stream viasteam reforming and/or autothermal reforming. When fuel processingassembly 24 generates the product hydrogen stream via pyrolysis orcatalytic partial oxidation, feed stream 26 does not contain water.

In some embodiments, feedstock delivery system 22 may be configured todeliver a hydrogen-production fluid 30 that contains a mixture of waterand a carbon-containing feedstock that is miscible with water (such asmethanol and/or another water-soluble alcohol). The ratio of water tocarbon-containing feedstock in such a fluid stream may vary according toone or more factors, such as the particular carbon-containing feedstockbeing used, user preferences, design of the fuel processing assembly,mechanism(s) used by the fuel processing assembly to generate theproduct hydrogen stream etc. For example, the molar ratio of water tocarbon may be approximately 1:1 to 3:1. Additionally, mixtures of waterand methanol may be delivered at or near a 1:1 molar ratio (37 weight %water, 63 weight % methanol), while mixtures of hydrocarbons or otheralcohols may be delivered at a water-to-carbon molar ratio greater than1:1.

When fuel processing assembly 24 generates product hydrogen stream 21via reforming, feed stream 26 may include, for example, approximately25-75 volume % methanol or ethanol (or another suitable water-misciblecarbon-containing feedstock) and approximately 25-75 volume % water. Forfeed streams that at least substantially include methanol and water,those streams may include approximately 50-75 volume % methanol andapproximately 25-50 volume % water. Streams containing ethanol or otherwater-miscible alcohols may contain approximately 25-60 volume % alcoholand approximately 40-75 volume % water. An example of a feed stream forhydrogen generating assembly 20 that utilizes steam reforming orautothermal reforming contains 69 volume % methanol and 31 volume %water.

Although feedstock delivery system 22 is shown to be configured todeliver a single feed stream 26, the feedstock delivery system may beconfigured to deliver two or more feed streams 26. Those streams maycontain the same or different feedstocks and may have differentcompositions, at least one common component, no common components, orthe same compositions. For example, a first feed stream may include afirst component, such as a carbon-containing feedstock and a second feedstream may include a second component, such as water. Additionally,although feedstock delivery system 22 may, in some embodiments, beconfigured to deliver a single fuel stream 28, the feedstock deliverysystem may be configured to deliver two or more fuel streams. The fuelstreams may have different compositions, at least one common component,no common components, or the same compositions. Moreover, the feed andfuel streams may be discharged from the feedstock delivery system indifferent phases. For example, one of the streams may be a liquid streamwhile the other is a gas stream. In some embodiments, both of thestreams may be liquid streams, while in other embodiments both of thestreams may be gas streams. Furthermore, although hydrogen generationassembly 20 is shown to include a single feedstock delivery system 22,the hydrogen generation assembly may include two or more feedstockdelivery systems 22.

Fuel processing assembly 24 may include a hydrogen-producing region 32configured to produce an output stream 34 containing hydrogen gas viaany suitable hydrogen-producing mechanism(s). The output stream mayinclude hydrogen gas as at least a majority component and may includeadditional gaseous component(s). Output stream 34 may therefore bereferred to as a “mixed gas stream” that contains hydrogen gas as itsmajority component but which includes other gases.

Hydrogen-producing region 32 may include any suitablecatalyst-containing bed or region. When the hydrogen-producing mechanismis steam reforming, the hydrogen-producing region may include a suitablesteam reforming catalyst 36 to facilitate production of output stream(s)34 from feed stream(s) 26 containing a carbon-containing feedstock andwater. In such an embodiment, fuel processing assembly 24 may bereferred to as a “steam reformer,” hydrogen-producing region 32 may bereferred to as a “reforming region,” and output stream 34 may bereferred to as a “reformate stream.” The other gases that may be presentin the reformate stream may include carbon monoxide, carbon dioxide,methane, steam, and/or unreacted carbon-containing feedstock.

When the hydrogen-producing mechanism is autothermal reforming,hydrogen-producing region 32 may include a suitable autothermalreforming catalyst to facilitate the production of output stream(s) 34from feed stream(s) 26 containing water and a carbon-containingfeedstock in the presence of air. Additionally, fuel processing assembly24 may include an air delivery assembly 38 configured to deliver airstream(s) to the hydrogen-producing region.

In some embodiments, fuel processing assembly 24 may include apurification (or separation) region 40, which may include any suitablestructure configured to produce at least one hydrogen-rich stream 42from output (or mixed gas) stream 34. Hydrogen-rich stream 42 mayinclude a greater hydrogen concentration than output stream 34 and/or areduced concentration of one or more other gases (or impurities) thatwere present in that output stream. Product hydrogen stream 21 includesat least a portion of hydrogen-rich stream 42. Thus, product hydrogenstream 21 and hydrogen-rich stream 42 may be the same stream and havethe same composition and flow rates. Alternatively, some of the purifiedhydrogen gas in hydrogen-rich stream 42 may be stored for later use,such as in a suitable hydrogen storage assembly and/or consumed by thefuel processing assembly. Purification region 40 also may be referred toas a “hydrogen purification device” or a “hydrogen processing assembly.”

In some embodiments, purification region 40 may produce at least onebyproduct stream 44, which may contain no hydrogen gas or some hydrogengas. The byproduct stream may be exhausted, sent to a burner assemblyand/or other combustion source, used as a heated fluid stream, storedfor later use, and/or otherwise utilized, stored, and/or disposed.Additionally, purification region 40 may emit the byproduct stream as acontinuous stream responsive to the deliver of output stream 34, or mayemit that stream intermittently, such as in a batch process or when thebyproduct portion of the output stream is retained at least temporarilyin the purification region.

Fuel processing assembly 24 may include one or more purification regionsconfigured to produce one or more byproduct streams containingsufficient amounts of hydrogen gas to be suitable for use as a fuelstream (or a feedstock stream) for a heating assembly for the fuelprocessing assembly. In some embodiments, the byproduct stream may havesufficient fuel value or hydrogen content to enable a heating assemblyto maintain the hydrogen-producing region at a desired operatingtemperature or within a selected range of temperatures. For example, thebyproduct stream may include hydrogen gas, such as 10-30 weight %hydrogen gas, 15-25 weight % hydrogen gas, 20-30 weight % hydrogen gas,at least 10 or 15 weight % hydrogen gas, at least 20 weight % hydrogengas, etc.

Purification region 40 may include any suitable structure configured toreduce the concentration of at least one component of output stream 21.In most applications, hydrogen-rich stream 42 will have a greaterhydrogen concentration than output stream (or mixed gas stream) 34. Thehydrogen-rich stream also may have a reduced concentration of one ormore non-hydrogen components that were present in output stream 34 withthe hydrogen concentration of the hydrogen-rich stream being more, thesame, or less than the output stream. For example, in conventional fuelcell systems, carbon monoxide may damage a fuel cell stack if it ispresent in even a few parts per million, while other non-hydrogencomponents that may be present in output stream 34, such as water, willnot damage the stack even if present in much greater concentrations.Therefore, in such an application, the purification region may notincrease the overall hydrogen concentration but will reduce theconcentration of one or more non-hydrogen components that are harmful,or potentially harmful, to the desired application for the producthydrogen stream.

Examples of suitable devices for purification region 40 include one ormore hydrogen-selective membranes 46, chemical carbon monoxide removalassemblies 48, and/or pressure swing adsorption (PSA) systems 50.Purification region 40 may include more than one type of purificationdevice and the devices may have the same or different structures and/oroperate by the same or difference mechanism(s). Fuel processing assembly24 may include at least one restrictive orifice and/or other flowrestrictor downstream of the purification region(s), such as associatedwith one or more product hydrogen stream(s), hydrogen-rich stream(s),and/or byproduct stream(s).

Hydrogen-selective membranes 46 are permeable to hydrogen gas, but areat least substantially (if not completely) impermeable to othercomponents of output stream 34. Membranes 46 may be formed of anyhydrogen-permeable material suitable for use in the operatingenvironment and parameters in which purification region 40 is operated.Examples of suitable materials for membranes 46 include palladium andpalladium alloys, and especially thin films of such metals and metalalloys. Palladium alloys have proven particularly effective, especiallypalladium with 35 weight % to 45 weight % copper. A palladium-copperalloy that contains approximately 40 weight % copper has provenparticularly effective, although other relative concentrations andcomponents may be used. Another especially effective alloy is palladiumwith 2 weight % to 10 weight % gold, especially palladium with 5 weight% gold. When palladium and palladium alloys are used, hydrogen-selectivemembranes 46 may sometimes be referred to as “foils.”

Chemical carbon monoxide removal assemblies 48 are devices thatchemically react carbon monoxide and/or other undesirable components ofoutput stream 34 to form other compositions that are not as potentiallyharmful. Examples of chemical carbon monoxide removal assemblies includewater-gas shift reactors that are configured to produce hydrogen gas andcarbon dioxide from water and carbon monoxide, partial oxidationreactors that are configured to convert carbon monoxide and oxygen(usually from air) into carbon dioxide, and methanation reactors thatare configured to convert carbon monoxide and hydrogen to methane andwater. Fuel processing assembly 24 may include more than one type and/ornumber of chemical removal assemblies 48.

Pressure swing adsorption (PSA) is a chemical process in which gaseousimpurities are removed from output stream 34 based on the principle thatcertain gases, under the proper conditions of temperature and pressure,will be adsorbed onto an adsorbent material more strongly than othergases. Typically, the non-hydrogen impurities are adsorbed and removedfrom output stream 34. Adsorption of impurity gases occurs at elevatedpressure. When the pressure is reduced, the impurities are desorbed fromthe adsorbent material, thus regenerating the adsorbent material.Typically, PSA is a cyclic process and requires at least two beds forcontinuous (as opposed to batch) operation. Examples of suitableadsorbent materials that may be used in adsorbent beds are activatedcarbon and zeolites. PSA system 50 also provides an example of a devicefor use in purification region 40 in which the byproducts, or removedcomponents, are not directly exhausted from the region as a gas streamconcurrently with the purification of the output stream. Instead, thesebyproduct components are removed when the adsorbent material isregenerated or otherwise removed from the purification region.

In FIG. 1, purification region 40 is shown within fuel processingassembly 24. The purification region may alternatively be separatelylocated downstream from the fuel processing assembly, as isschematically illustrated in dash-dot lines in FIG. 1. Purificationregion 40 also may include portions within and external to the fuelprocessing assembly.

Fuel processing assembly 24 also may include a temperature modulatingassembly in the form of a heating assembly 52. The heating assembly maybe configured to produce at least one heated exhaust stream (orcombustion stream) 54 from at least one heating fuel stream 28,typically as combusted in the presence of air. Heated exhaust stream 54is schematically illustrated in FIG. 1 as heating hydrogen-producingregion 32. Heating assembly 52 may include any suitable structureconfigured to generate the heated exhaust stream, such as a burner orcombustion catalyst in which a fuel is combusted with air to produce theheated exhaust stream. The heating assembly may include an ignitor orignition source 58 that is configured to initiate the combustion offuel. Examples of suitable ignition sources include one or more sparkplugs, glow plugs, combustion catalyst, pilot lights, piezoelectricignitors, spark igniters, hot surface igniters, etc.

In some embodiments, heating assembly 52 may include a burner assembly60 and may be referred to as a combustion-based, or combustion-driven,heating assembly. In a combustion-based heating assembly, heatingassembly 52 may be configured to receive at least one fuel stream 28 andto combust the fuel stream in the presence of air to provide a hotcombustion stream 54 that may be used to heat at least thehydrogen-producing region of the fuel processing assembly. Air may bedelivered to the heating assembly via a variety of mechanisms. Forexample, an air stream 62 may be delivered to the heating assembly as aseparate stream, as shown in FIG. 1. Alternatively, or additionally, airstream 62 may be delivered to the heating assembly with at least one ofthe fuel streams 28 for heating assembly 52 and/or drawn from theenvironment within which the heating assembly is utilized.

Combustion stream 54 may additionally, or alternatively, be used to heatother portions of the fuel processing assembly and/or fuel cell systemswith which the heating assembly is used. Additionally, otherconfiguration and types of heating assemblies 52 may be used. Forexample, heating assembly 52 may be an electrically powered heatingassembly that is configured to heat at least hydrogen-producing region32 of fuel processing assembly 24 by generating heat using at least oneheating element, such as a resistive heating element. In thoseembodiments, heating assembly 52 may not receive and combust acombustible fuel stream to heat the hydrogen-producing region to asuitable hydrogen-producing temperature. Examples of heating assembliesare disclosed in U.S. Pat. No. 7,632,322, the complete disclosure ofwhich is hereby incorporated by reference for all purposes.

Heating assembly 52 may be housed in a common shell or housing with thehydrogen-producing region and/or separation region (as further discussedbelow). The heating assembly may be separately positioned relative tohydrogen-producing region 32 but in thermal and/or fluid communicationwith that region to provide the desired heating of at least thehydrogen-producing region. Heating assembly 52 may be located partiallyor completely within the common shell, and/or at least a portion (orall) of the heating assembly may be located external that shell. Whenthe heating assembly is located external the shell, the hot combustiongases from burner assembly 60 may be delivered via suitable heattransfer conduits to one or more components within the shell.

The heating assembly also may be configured to heat feedstock deliverysystem 22, the feedstock supply streams, hydrogen-producing region 32,purification (or separation) region 40, or any suitable combination ofthose systems, streams, and regions. Heating of the feedstock supplystreams may include vaporizing liquid reactant streams or components ofthe hydrogen-production fluid used to produce hydrogen gas in thehydrogen-producing region. In that embodiment, fuel processing assembly24 may be described as including a vaporization region 64. The heatingassembly may additionally be configured to heat other components of thehydrogen generation assembly. For example, the heated exhaust stream maybe configured to heat a pressure vessel and/or other canister containingthe heating fuel and/or the hydrogen-production fluid that forms atleast portions of feed stream 26 and fuel stream 28.

Heating assembly 52 may achieve and/or maintain in hydrogen-producingregion 32 any suitable temperatures. Steam reformers typically operateat temperatures in the range of 200° C. and 900° C. However,temperatures outside this range are within the scope of this disclosure.When the carbon-containing feedstock is methanol, the steam reformingreaction will typically operate in a temperature range of approximately200-500° C. Example subsets of that range include 350-450° C., 375-425°C., and 375-400° C. When the carbon-containing feedstock is ahydrocarbon, ethanol or another alcohol, a temperature range ofapproximately 400-900° C. will typically be used for the steam reformingreaction. Example subsets of that range include 750-850° C., 725-825°C., 650-750° C., 700-800° C., 700-900° C., 500-800° C., 400-600° C., and600-800° C. Hydrogen-producing region 32 may include two or more zones,or portions, each of which may be operated at the same or at differenttemperatures. For example, when the hydrogen-production fluid includes ahydrocarbon, hydrogen-producing region 32 may include two differenthydrogen-producing portions, or regions, with one operating at a lowertemperature than the other to provide a pre-reforming region. In thoseembodiments, the fuel processing assembly may also be referred to asincluding two or more hydrogen-producing regions.

Fuel stream 28 may include any combustible liquid(s) and/or gas(es) thatare suitable for being consumed by heating assembly 52 to provide thedesired heat output. Some fuel streams may be gases when delivered andcombusted by heating assembly 52, while others may be delivered to theheating assembly as a liquid stream. Examples of suitable heating fuelsfor fuel streams 28 include carbon-containing feedstocks, such asmethanol, methane, ethane, ethanol, ethylene, propane, propylene,butane, etc. Additional examples include low molecular weightcondensable fuels, such as liquefied petroleum gas, ammonia, lightweightamines, dimethyl ether, and low molecular weight hydrocarbons. Yet otherexamples include hydrogen and carbon monoxide. In embodiments ofhydrogen generation assembly 20 that include a temperature modulatingassembly in the form of a cooling assembly instead of a heating assembly(such as may be used when an exothermic hydrogen-generatingprocess—e.g., partial oxidation—is utilized instead of an endothermicprocess such as steam reforming), the feedstock delivery system may beconfigured to supply a fuel or coolant stream to the assembly. Anysuitable fuel or coolant fluid may be used.

Fuel processing assembly 24 may additionally include a shell or housing66 in which at least hydrogen-producing region 32 is contained, as shownin FIG. 1. In some embodiments, vaporization region 64 and/orpurification region 40 may additionally be contained within the shell.Shell 66 may enable components of the steam reformer or other fuelprocessing mechanism to be moved as a unit. The shell also may protectcomponents of the fuel processing assembly from damage by providing aprotective enclosure and/or may reduce the heating demand of the fuelprocessing assembly because components may be heated as a unit. Shell 66may include insulating material 68, such as a solid insulating material,blanket insulating material, and/or an air-filled cavity. The insulatingmaterial may be internal the shell, external the shell, or both. Whenthe insulating material is external a shell, fuel processing assembly 24may further include an outer cover or jacket 70 external the insulation,as schematically illustrated in FIG. 1. The fuel processing assembly mayinclude a different shell that includes additional components of thefuel processing assembly, such as feedstock delivery system 22 and/orother components.

One or more components of fuel processing assembly 24 may either extendbeyond the shell or be located external the shell. For example,purification region 40 may be located external shell 66, such as beingspaced-away from the shell but in fluid communication by suitablefluid-transfer conduits. As another example, a portion ofhydrogen-producing region 32 (such as portions of one or more reformingcatalyst beds) may extend beyond the shell, such as indicatedschematically with a dashed line representing an alternative shellconfiguration in FIG. 1. Examples of suitable hydrogen generationassemblies and its components are disclosed in U.S. Pat. Nos. 5,861,137;5,997,594; and 6,221,117, the complete disclosures of which are herebyincorporated by reference for all purposes.

Another example of hydrogen generation assembly 20 is shown in FIG. 2,and is generally indicated at 72. Unless specifically excluded, hydrogengeneration assembly 72 may include one or more components of hydrogengeneration assembly 20. Hydrogen-generation assembly 72 may include afeedstock delivery system 74, a vaporization region 76, ahydrogen-producing region 78, and a heating assembly 80, as shown inFIG. 2. In some embodiments, hydrogen generation assembly 20 also mayinclude a purification region 82.

The feedstock delivery system may include any suitable structureconfigured to deliver one or more feed and/or fuel streams to one ormore other components of the hydrogen-generation assembly. For example,feedstock delivery system may include a feedstock tank (or container) 84and a pump 86. The feedstock tank may contain any suitablehydrogen-production fluid 88, such as water and a carbon-containingfeedstock (e.g., a methanol/water mixture). Pump 86 may have anysuitable structure configured to deliver the hydrogen-production fluid,which may be in the form of at least one liquid-containing feed stream90 that includes water and a carbon-containing feedstock, tovaporization region 76 and/or hydrogen-producing region 78.

Vaporization region 76 may include any suitable structure configured toreceive and vaporize at least a portion of a liquid-containing feedstream, such as liquid-containing feed stream 90. For example,vaporization region 76 may include a vaporizer 92 configured to at leastpartially transform liquid-containing feed stream 90 into one or morevapor feed streams 94. The vapor feed streams may, in some embodiments,include liquid. An example of a suitable vaporizer is a coiled tubevaporizer, such as a coiled stainless steel tube.

Hydrogen-producing region 78 may include any suitable structureconfigured to receive one of more feed streams, such as vapor feedstream(s) 94 from the vaporization region, to produce one or more outputstreams 96 containing hydrogen gas as a majority component and othergases. The hydrogen-producing region may produce the output stream viaany suitable mechanism(s). For example, hydrogen-producing region 78 maygenerate output stream(s) 96 via a steam reforming reaction. In thatexample, hydrogen-producing region 78 may include a steam reformingregion 97 with a reforming catalyst 98 configured to facilitate and/orpromote the steam reforming reaction. When hydrogen-producing region 78generates output stream(s) 96 via a steam reforming reaction, hydrogengeneration assembly 72 may be referred to as a “steam reforming hydrogengeneration assembly” and output stream 96 may be referred to as a“reformate stream.”

Heating assembly 80 may include any suitable structure configured toproduce at least one heated exhaust stream 99 for heating one or moreother components of the hydrogen generation assembly 72. For example,the heating assembly may heat the vaporization region to any suitabletemperature(s), such as at least a minimum vaporization temperature orthe temperature in which at least a portion of the liquid-containingfeed stream is vaporized to form the vapor feed stream. Additionally, oralternatively, heating assembly 80 may heat the hydrogen-producingregion to any suitable temperature(s), such as at least a minimumhydrogen-producing temperature or the temperature in which at least aportion of the vapor feed stream is reacted to produce hydrogen gas toform the output stream. The heating assembly may be in thermalcommunication with one or more components of the hydrogen generationassembly, such as the vaporization region and/or hydrogen-producingregion.

The heating assembly may include a burner assembly 100, at least one airblower 102, and an igniter assembly 104, as shown in FIG. 2. The burnerassembly may include any suitable structure configured to receive atleast one air stream 106 and at least one fuel stream 108 and to combustthe at least one fuel stream within a combustion region 110 to produceheated exhaust stream 99. The fuel stream may be provided by feedstockdelivery system 74 and/or purification region 82. The combustion regionmay be contained within an enclosure of the hydrogen generationassembly. Air blower 102 may include any suitable structure configuredto generate air stream(s) 106. Igniter assembly 104 may include anysuitable structure configured to ignite fuel stream(s) 108.

Purification region 82 may include any suitable structure configured toproduce at least one hydrogen-rich stream 112, which may include agreater hydrogen concentration than output stream 96 and/or a reducedconcentration of one or more other gases (or impurities) that werepresent in that output stream. The purification region may produce atleast one byproduct stream or fuel stream 108, which may be sent toburner assembly 100 and used as a fuel stream for that assembly, asshown in FIG. 2. Purification region 82 may include a flow restrictingorifice 111, a filter assembly 114, a membrane assembly 116, and amethanation reactor assembly 118. The filter assembly (such as one ormore hot gas filters) may be configured to remove impurities from outputstream 96 prior to the hydrogen purification membrane assembly.

Membrane assembly 116 may include any suitable structure configured toreceive output or mixed gas stream(s) 96 that contains hydrogen gas andother gases, and to generate permeate or hydrogen-rich stream(s) 112containing a greater concentration of hydrogen gas and/or a lowerconcentration of other gases than the mixed gas stream. Membraneassembly 116 may incorporate hydrogen-permeable (or hydrogen-selective)membranes that are planar or tubular, and more than onehydrogen-permeable membrane may be incorporated into membrane assembly116. The permeate stream(s) may be used for any suitable applications,such as for one or more fuel cells. In some embodiments, the membraneassembly may generate a byproduct or fuel stream 108 that includes atleast a substantial portion of the other gases. Methanation reactorassembly 118 may include any suitable structure configured to convertcarbon monoxide and hydrogen to methane and water. Although purificationregion 82 is shown to include flow restricting orifice 111, filterassembly 114, membrane assembly 116, and methanation reactor assembly118, the purification region may have less than all of those assemblies,and/or may alternatively, or additionally, include one or more othercomponents configured to purify output stream 96. For example,purification region 82 may include only membrane assembly 116.

In some embodiments, hydrogen generation assembly 72 may include a shellor housing 120 which may at least partially contain one or more othercomponents of that assembly. For example, shell 120 may at leastpartially contain vaporization region 76, hydrogen-producing region 78,heating assembly 80, and/or purification region 82, as shown in FIG. 2.Shell 120 may include one or more exhaust ports 122 configured todischarge at least one combustion exhaust stream 124 produced by heatingassembly 80.

Hydrogen generation assembly 72 may, in some embodiments, include acontrol system 126, which may include any suitable structure configuredto control operation of hydrogen generation assembly 72. For example,control assembly 126 may include a control assembly 128, at least onevalve 130, at least one pressure relief valve 132, and one or moretemperature measurement devices 134. Control assembly 128 may detecttemperatures in the hydrogen-producing region and/or purificationregions via the temperature measurement device 134, which may includeone or more thermocouples and/or other suitable devices. Based on thedetected temperatures, the control assembly and/or an operator of thecontrol system may adjust delivery of feed stream 90 to vaporizationregion 76 and/or hydrogen-producing region 78 via valve(s) 130 andpump(s) 86. Valve(s) 130 may include a solenoid valve and/or anysuitable valve(s). Pressure relief valve(s) 132 may be configured toensure that excess pressure in the system is relieved.

In some embodiments, hydrogen generation assembly 72 may include a heatexchange assembly 136, which may include one or more heat exchangers 138configured to transfer heat from one portion of the hydrogen generationassembly to another portion. For example, heat exchange assembly 136 maytransfer heat from hydrogen-rich stream 112 to feed stream 90 to raisethe temperature of the feed stream prior to entering vaporization region76, as well as to cool hydrogen-rich stream 112.

Another example of hydrogen generation assembly 20 is generallyindicated at 140 in FIG. 3. Unless specifically excluded, hydrogengeneration assembly 140 may include one or more components of one ormore other hydrogen generation assemblies described in this disclosure.Hydrogen generation assembly 140 may include a feedstock delivery systemor feed assembly 142 and a fuel processing assembly 144 configured toreceive at least one feed stream from the feedstock delivery system andproduce one or more product hydrogen stream(s), such as a hydrogen gasstream, from the feed stream(s).

The feedstock delivery system may include any suitable structureconfigured to deliver one or more feed and/or fuel streams to one ormore other components of the hydrogen generation assembly, such as fuelprocessing assembly 144. For example, the feedstock delivery system mayinclude a feedstock tank or feed tank (and/or container) 146, a feedconduit 148, a pump 150, and a control system 152. The feed tank maycontain feedstock for one or more feed streams of the fuel processingassembly. For example, feed tank 146 may contain any suitablehydrogen-production fluid, such as water and a carbon-containingfeedstock (e.g., a methanol/water mixture).

Feed conduit 148 may fluidly connect feed tank 146 with fuel processingassembly 144. The feed conduit may include a feed portion 154 and abypass portion 156. The bypass portion may be configured to preventoverpressurization in the feed conduit, in the fuel processing assembly,and/or in one or more other components of hydrogen generation assembly140. For example, bypass portion 156 may include a valve assembly 158,such as a pressure relief valve or a check valve.

Pump 150 may have any suitable structure configured to deliver one ormore feed and/or fuel streams to the fuel processing assembly at aplurality of flowrates to fuel processing assembly 144 via, for example,feed conduit 148. For example, pump 150 may be a variable-speed pump (ora pump that includes a variable speed motor) that injects the feedand/or fuel streams into the fuel processing assembly under pressure.The pump may operate at a speed based on a control signal from thecontrol system. For example, pump 150 may operate or turn at a higherspeed (which results in the pump discharging the feed and/or fuelstreams at a higher flowrate) when the control signal increases inmagnitude, while the pump may operate or turn at a lower speed (whichresults in the pump discharging the feed and/or fuel streams at a lowerflowrate) when the control signal decreases in magnitude.

Pressure in the fuel processing assembly (such as in thehydrogen-producing region of the fuel processing assembly) may increasewith higher pump flowrates and may decrease with lower pump flowrates.For example, one or more fixed flow restriction devices in the fuelprocessing assembly may cause a proportional increase in pressure withhigher pump flowrates, and a proportional decrease in pressure withlower pump flowrates. Because feed conduit 148 fluidly connects thefeedstock delivery system and the fuel processing assembly, an increase(or decrease) in pressure in the fuel processing assembly may result inan increase (or decrease) in pressure in the feed conduit downstreamfrom pump 150.

Control system 152 may include any suitable structure configured tocontrol and/or operate pump 150 and/or other controlled devices ofhydrogen generation assembly 140. For example, control system 152 mayinclude a sensor assembly 160, a control assembly 162, and communicationlinkages 164.

The sensor assembly may include any suitable structure configured todetect and/or measure one or more suitable operating variables and/orparameters in the hydrogen generation assembly and/or generate one ormore signals based on the detected and/or measured operating variable(s)and/or parameter(s). For example, the sensor assembly may detect mass,volume, flow, temperature, electrical current, pressure, refractiveindex, thermal conductivity, density, viscosity, optical absorbance,electrical conductivity, and/or other suitable variable(s), and/orparameter(s). In some embodiments, the sensor assembly may detect one ormore triggering events. A “triggering event,” as used herein, is ameasurable event in which a predetermined threshold value or range ofvalues representative of a predetermined amount of one or more of thecomponents forming one or more streams associated with the hydrogengeneration assembly is reached or exceeded.

For example, sensor assembly 160 may include one or more sensors 166configured to detect pressure, temperature, flowrate, volume, and/orother parameters. Sensors 166 may, for example, include at least onefeed sensor 168 configured to detect one or more suitable operatingvariables, parameters, and/or triggering events in feed conduit 148. Thefeed sensor may be configured to detect, for example, pressure in thefeed conduit and/or generate one or more signals based on the detectedpressure.

Control assembly 162 may be configured to communicate with sensorassembly 160 and pump 150 (and/or other controlled devices of hydrogengeneration assembly 140) via communication linkages 164. For example,control assembly 162 may include any suitable structure configured toselect a flowrate from the plurality of flowrates of pump 150 based onthe detected pressure in the feed conduit, and/or to operate the pump atthe selected flowrate. Communication linkages 164 may be any suitablewired and/or wireless mechanism for one- or two-way communicationbetween the corresponding devices, such as input signals, commandsignals, measured parameters, etc.

Control assembly 162 may, for example, include at least one processor170, as shown in FIG. 4. The processor may communicate with sensorassembly 160 and pump 150 and/or other controlled-devices viacommunication linkages 148. Processor 170 may have any suitable form,such as a computerized device, software executing on a computer, anembedded processor, programmable logic controller, an analog device(with one or more resistors), and/or functionally equivalent devices.The control assembly may include any suitable software, hardware, and/orfirmware. For example, control assembly 162 may include memory device(s)172 in which preselected, preprogrammed, and/or user-selected operatingparameters may be stored. The memory device may include volatileportion(s), nonvolatile portion(s), and/or both.

In some embodiments, processor 170 may be in the form of a signalconditioner 174, which may include any suitable structure configured tocondition one or more signals received from sensor assembly 160. Thesignal conditioner may amplify, filter, convert, invert, range match,isolate, and/or otherwise modify one or more signals received from thesensor assembly such that the conditioned signals are suitable fordownstream components. For example, signal conditioner 174 may invertone or more signals received from sensor assembly 160. “Invert,” as usedherein, refers to one or more of the following: converting a signal witha characteristic having ascending values to a signal with thecharacteristic having descending values, converting a signal with acharacteristic having descending values to a signal with thecharacteristic having ascending values, converting a signal with acharacteristic having a high value to a signal with the characteristichaving a low value (or having the highest value to the lowest value),and/or converting a signal with a characteristic having a low value to asignal with the characteristic having a high value (or having the lowestvalue to the highest value). Characteristics of the signals may includevoltage, current, etc. One or more of the converted values may matchand/or correspond to values from the original signal, such as convertingthe highest original value to the lowest original value and/orconverting the lowest original value to the highest original value.Alternatively, one or more of the converted values may be different fromthe original values of the signals.

In some embodiments, control assembly 162 may include a user interface176, as shown in FIG. 4. The user interface may include any suitablestructure configured to allow a user to monitor and/or interact withoperation of processor 170. For example, user interface 176 may includea display region 178, a user input device 180, and/or a user-signalingdevice 182, as shown in FIG. 4. The display region may include a screenand/or other suitable display mechanism in which information ispresented to the user. For example, display region 178 may displaycurrent values measured by one or more sensors 166, current operatingparameters of the hydrogen generation assembly, stored threshold valuesor ranges, previously measured values, and/or other informationregarding the operation and/or performance of the hydrogen generationassembly.

User input device 180 may include any suitable structure configured toreceive input from the user and send that input to processor 170. Forexample, the user input device may include rotary dials, switches,push-buttons, keypads, keyboards, a mouse, touch screens, etc. Userinput device 180 may, for example, enable a user to specify how signalsfrom sensor assembly 160 will be conditioned, such as whether the signalwill be inverted, what the range of values of the inverted signal shouldbe, etc. User-signaling device 182 may include any suitable structureconfigured to alert a user when an acceptable threshold level has beenexceeded. For example, the user-signaling device may include an alarm,lights, and/or other suitable mechanism(s) for alerting a user.

In some embodiments, control assembly 162 may be configured to onlycondition signals received from sensor assembly 160 via signalconditioner 168 without additional processing of the signal and/orsending a different signal. In other words, the signal(s) from sensorassembly 160 may be conditioned via signal conditioner 168 and theconditioned signals may be sent to pump 150 and/or other controlleddevice(s) via communication linkages 164 to operate the pump and/orother controlled devices without additional processing by the controlassembly and/or other assemblies.

The conditioned signal (such as an inverted signal) may be configured,for example, to select a flowrate for pump 150 from the plurality offlowrates. When the conditioned signal is configured to select aflowrate for the pump, the control assembly may be described as beingconfigured to select the flowrate based on (or based solely on) theconditioned signal.

An example of controlling pump 150 with a conditioned signal is shown ingraph 184 in FIG. 5. Sensor assembly 160 may include feed sensor 168that detects pressure and sends a detection signal 186 to controlassembly 162 based on the detected pressure. The detection signal may bea voltage signal as shown in FIG. 5, a current signal, and/or othersuitable signals that are proportional to the detected pressure. Thedetection signal(s) may be any suitable voltage(s) and/or current(s),such as 0-5 volts and/or 4-20 milliampere (mA).

Control assembly 162 may condition (such as invert) the detection signalinto a conditioned signal 188 such that the conditioned signal isconfigured to select one or more parameters (such as flowrate and/orspeed) for pump 150 and/or other controlled devices. The conditionedsignal(s) may be any suitable voltage(s) and/or current(s), such as 0-5volts and/or 4-20 mA. The voltages and pressure shown in FIG. 5 are onlyone example of the various voltages and pressures that may be generatedand/or detected by control system 152. In other words, control system152 is not limited to operation in the voltages and pressures shown inthat figure.

Another example of hydrogen generation assembly 20 is generallyindicated at 190 in FIG. 6. Unless specifically excluded, hydrogengeneration assembly 190 may include one or more components of one ormore other hydrogen generation assemblies described in this disclosure.Hydrogen generation assembly 190 may include a feedstock delivery systemor feed assembly 192 and a fuel processing assembly 194 configured toreceive at least one feed stream from the feedstock delivery system andproduce one or more product hydrogen stream(s), such as a hydrogen gasstream, from the feed stream(s).

The feedstock delivery system may include a feedstock tank or feed tank(and/or container) 196, a feed conduit 198, a pump 200, and a controlsystem 202. The feed tank may contain feedstock for one or more feedstreams of the fuel processing assembly. Feed conduit 198 may fluidlyconnect feed tank 196 with fuel processing assembly 194. The feedconduit may include a feed portion 204 and a bypass portion 206. Thebypass portion may be configured to prevent overpressurization inhydrogen generation assembly 190. For example, bypass portion 206 mayinclude a pressure relief valve 208.

Pump 200 may have any suitable structure configured to deliver one ormore feed and/or fuel streams to the fuel processing assembly at aplurality of flowrates to fuel processing assembly 194 via, for example,feed conduit 198. For example, pump 200 may be a variable-speed pump (ora pump that includes a variable speed motor) that injects the feedand/or fuel streams into the fuel processing assembly under pressure.The pump may operate at a speed based on a control signal from thecontrol system.

Control system 202 may include any suitable structure configured tocontrol and/or operate pump 200 and/or other controlled devices ofhydrogen generation assembly 190. For example, control system 202 mayinclude at least one pressure transducer 210, a control assembly 212,and communication linkages 214. Pressure transducer 210 may beconfigured to detect pressure in feed conduit 198. Although pressuretransducer 210 is shown to be adjacent to pump 200 and/or bypass portion206, the pressure transducer may be positioned in any suitable portionsalong the feed portion.

Control assembly 212 may include a power supply assembly 216 and asignal conditioner assembly 218. The power supply assembly may includeany suitable structure configured to provide suitable power to thesignal conditioner assembly. For example, the power supply assembly mayinclude one or more batteries, one or more solar panels, one or moreconnectors for connecting to a DC or AC power source, etc. In someembodiments, power supply assembly 216 may include a DC power supply,which may provide the same voltage as is required to operate pump 200and/or pressure transducer 210.

Signal conditioner assembly 218 may include any suitable structureconfigured to condition one or more signals received from pressuretransducer 210 such that one or more of the conditioned signals may beused to operate pump 200. For example, signal conditioner assembly 218may invert the pressure signals (or transducer signals) received fromthe pressure transducer and relay the inverted signals via communicationlinkages 214 to pump 200. The inverted signals may be configured toselect a speed and/or flowrate for pump 200 among the plurality ofspeeds and/or flowrates for the pump. When the inverted signals are usedto control the pump's speed, the signals may be referred to as “speedcontrol signals.”

An example of a purge assembly of the hydrogen generation assembliesdescribed in the present disclosure is shown in FIG. 7 and is generallyindicated at 220. The purge assembly may include any suitable structureconfigured to purge one or more other portions of a hydrogen generationassembly. Purge assembly 220 may be configured to purge one or moregases from reactor(s), purifier(s), fuel processing assembly(ies),and/or other component(s) and/or device(s) of hydrogen generationassemblies of the present disclosure and/or other hydrogen generationassemblies. For example, purge assembly 220 may include a pressurizedgas assembly 222, a purge conduit 224, and a valve assembly 226. Purgeconduit 224 may be configured to fluidly connect the pressurized gasassembly and one or more other portions of the hydrogen generationassembly.

Pressurized gas assembly 222 may include any suitable structureconfigured to connect to and/or receive at least one gas supply assembly228. For example, pressurized gas assembly 222 may include any suitableconnectors, piping, valves, and/or other components configured toconnect to and/or receive gas supply assembly 228. The gas supplyassembly may include one or more containers of pressurized gas (such asone or more cartridges and/or cylinders) and/or one or more tanks ofpressurized gas. The gas supply assembly may include any suitablepressurized gas configured to purge one or more other components of thehydrogen generation assemblies described in the present disclosure. Forexample, gas supply assembly may include compressed carbon dioxide orcompressed nitrogen.

Purge conduit 224 may be configured to fluidly connect the pressurizedgas assembly and one or more other portions of the hydrogen generationassembly, such as the fuel processing assembly. The purge conduit mayinclude any suitable connectors, piping, valves, and/or other componentsto provide for the fluid connection between the above assemblies.

Valve assembly 226 may include any suitable structure configured tomanage flow of the pressurized gas through purge conduit 224 frompressurized gas assembly 222 to one or more other portions of thehydrogen generation assembly. For example, valve assembly 226 may beconfigured to allow at least one pressurized gas to flow through thepurge conduit from the pressurized gas assembly to one or more otherportions of the hydrogen generation assembly and/or to prevent the atleast one pressurized gas to flow through the purge conduit from thepressurized gas assembly to one or more other portions of the hydrogengeneration assembly. The valve assembly may be configured to allow orprevent flow based on one or more detected variable(s), parameter(s)and/or triggering event(s). For example, the valve assembly may beconfigured to allow flow of at least one pressurized gas from thepressurized gas assembly to one or more other portions of the hydrogengeneration assembly when power to one or more portions of the hydrogengeneration assembly is interrupted.

In some embodiments, a control system 230 may control one or more valvesof valve assembly 226. Control system 230 may also control one or moreother components of the hydrogen generation assembly, or may bededicated to controlling only purge assembly 220. In some embodiments,valve assembly 226 may be configured to manage flow in the purge conduitindependent of control system 230 and/or any control system of thehydrogen generation assembly. In other words, valve assembly 226 may beconfigured to selectively allow and prevent flow without direction fromcontrol system 230 and/or any control system of the hydrogen generationassembly.

The purge assembly may be located within enclosure or shell 66, externalto the shell, or partially within the shell and partially external theshell. In some embodiments, at least a portion of the fuel processingassembly may be contained within an enclosure and at least a portion ofthe purge assembly may be contained within the enclosure, as shown inFIG. 1.

Purge assembly 220 may be connected to any suitable other component(s)of the hydrogen generation assembly. For example, as shown in FIG. 2,purge assembly 220 may be connected to the feed conduit either upstreamof heat exchange assembly 136 (such as shown via purge conduit 224),and/or downstream of the heat exchange assembly (such as shown via apurge conduit 225). In some embodiments, the feed conduit of thehydrogen generation assembly may include a check valve 232 to preventbackflow of the pressurized gas into the feedstock delivery system, suchas when the pump does not prevent backflow. The pressurized gas from thepurge assembly may exit the hydrogen generation assembly at any suitableportions, such as the burner and/or the product hydrogen line.

Another example of purge assembly 220 is shown in FIG. 8 and isgenerally indicated at 232. Purge assembly 232 may include a pressurizedgas assembly 234, a purge conduit 236, and a valve assembly 238. Thepressurized gas assembly may include any suitable structure configuredto receive at least one pressurized gas container 240 having at leastone pressurized gas. Purge conduit 236 may include any suitablestructure configured to fluidly connect pressurized gas assembly 234 andone or more other portions of the hydrogen generation assembly.

Valve assembly 238 may include any suitable structure configured tomanage flow of the at least one pressurized gas through the purgeconduit from the pressurized gas assembly to one or more other portionsof the hydrogen generation assembly. For example, valve assembly 238 mayinclude a manual valve 240 and a solenoid valve (or purge solenoidvalve) 242, as shown in FIG. 8. The manual valve may be closed toisolate the pressurized gas assembly from one or more other portions ofthe hydrogen generation assembly, such as when installing or connectinga compressed or pressurized gas canister to the pressurized gasassembly. Manual valve 240 may then be opened to allow the solenoidvalve to manage flow of the gas through the purge conduit from thepressurized gas assembly to one or more other portions of the hydrogengeneration assembly. Manual valve 240 may sometimes be referred to as a“manual isolation valve.”

Solenoid valve 242 may include at least one solenoid or purge solenoid244 and at one valve or purge valve 246. The valve may be configured tomove among a plurality of positions, including between a closed positionand an open position. In the closed position, the pressurized gasassembly is isolated from one or more other portions of the hydrogengeneration assembly and the pressurized gas does not flow through thepurge conduit from the pressurized gas assembly. In the open position,the pressurized gas assembly is in fluid communication with one or moreother portions of the hydrogen generation assembly and pressurized gasis allowed to flow through the purge conduit from the pressurized gasassembly. Solenoid 244 may be configured to move valve 226 between theopen and closed positions based on one or more detected variable(s),parameter(s) and/or triggering event(s). Solenoid valve 242 may, forexample, be configured to allow flow of at least one pressurized gasfrom the pressurized gas assembly to one or more other portions of thehydrogen generation assembly when power to the solenoid and/or one ormore portions of the hydrogen generation assembly is interrupted, suchas when power to the fuel processing assembly is interrupted.

For example, valve 246 may be configured to be in the open positionwithout power to solenoid 244 (may also be referred to as “normallyopen”), such as via urging of one or more bias elements or springs (notshown). Additionally, valve 246 may be configured to be in the closedposition with power to solenoid 244 (which may move the valve to theclosed position against urging of the bias element(s)). Thus, a loss ofelectrical power to one or more portions of the hydrogen generationassembly (and/or a loss of electrical power to solenoid 244) may causevalve 246 to automatically move from the closed position to the openposition. In other words, valve 246 of solenoid valve 242 may beconfigured to be in the closed position when there is power to thesolenoid and/or one or more portions of the hydrogen generation assembly(such as the fuel processing assembly), and may automatically move tothe open position when power to the solenoid and/or one or more portionsof the hydrogen generation assembly is interrupted.

In some embodiments, solenoid valve 242 may be controlled by a controlsystem 248. For example, control system 248 may be configured to send acontrol signal to solenoid 244 and the solenoid may be configured tomove valve 246 to the closed position when the control signal isreceived. Additionally, valve 246 may be configured to automaticallymove to the open position when the solenoid does not receive a controlsignal from the control system. Control system 248 may control one ormore other components of the hydrogen generation assembly or may beseparate from any control system. The solenoid valve may, in someembodiments, be controlled by both the control system and whether poweris supplied to the solenoid.

In some embodiments, purge assembly 220 may include a flow-restrictionorifice 250, which may be configured to reduce or limit flow rate of thepressurized gas discharged from the pressurized gas assembly. Forexample, when the pressurized gas is nitrogen, the flow-restrictionorifice may reduce or limit flow rate of the nitrogen gas to avoidoverpressure in one or more other components of the hydrogen generationassembly, such as in the reformer and/or purifier. However, when thepressurized gas is liquefied compressed gas, such as carbon dioxide, thepurge assembly may not include the flow-restriction orifice.

The purge assemblies of the present disclosure may be used as part of(or in) any suitable hydrogen generation assembly, such as a hydrogengeneration assembly with a reformer but without a hydrogen purifier, ahydrogen generation assembly with a hydrogen purifier but without areformer, a hydrogen generation assembly with a methanol/water reformer,a natural gas reformer, a LPG reformer, etc.

Another example of hydrogen generation assembly 20 is generallyindicated at 252 in FIG. 9. Unless specifically excluded, hydrogengeneration assembly 252 may include one or more components of one ormore other hydrogen generation assemblies described in this disclosure.Hydrogen generation assembly 252 may include an enclosure or shell 254,a hydrogen-producing region 256, a heating assembly 258, and an exhaustmanagement assembly 260. The enclosure or shell may include any suitablestructure configured to at least partially contain one or more othercomponents of hydrogen generation assembly 252 and/or provide insulation(such as thermal insulation) for those component(s). The enclosure maydefine an insulated zone or insulated hot zone 261 for the componentswithin the enclosure. Enclosure 254 may include at least one exhaustport 262 configured to exhaust gases within the enclosure to theenvironment and/or to an exhaust collection system.

Hydrogen-producing region 256 may be partially or fully contained withinthe enclosure. The hydrogen-producing region may receive one or morefeed streams 264 and produce an output stream 266 containing hydrogengas via any suitable hydrogen-producing mechanism(s), such as steamreforming, autothermal reforming, etc. The output stream may includehydrogen gas as at least a majority component and may include additionalgases. When hydrogen generation assembly 252 is a steam reforminghydrogen generation assembly, then the hydrogen-producing region may bereferred to as being configured to produce, via a steam reformingreaction, a reformate stream 266.

In some embodiments, hydrogen generation assembly 252 may include apurification region 268, which may include any suitable structureconfigured to produce at least one hydrogen-rich (or permeate) stream270 from output (or reformate) stream 266 and at least one byproductstream 272 (which may contain no or some hydrogen gas). For example, thepurification region may include one or more hydrogen-selective membranes274. The hydrogen-selective membrane(s) may be configured to produce atleast part of the permeate stream from the portion of the reformatestream that passes through the hydrogen-selective membrane(s), and toproduce at least part of the byproduct stream from the portion of thereformate stream that does not pass through the hydrogen-selectivemembrane(s). In some embodiments, hydrogen generation assembly 252 mayinclude a vaporization region 276, which may include any suitablestructure configured to vaporize the feed stream(s) containing one ormore liquid(s).

Heating assembly 258 may be configured to receive at least one airstream 278 and at least one fuel stream 280 and to combust the fuelstream(s) within a combustion region 282 contained within enclosure 254.Fuel stream 280 may be produced from the hydrogen-producing region(and/or the purification region), and/or may be produced independent ofthe hydrogen generation assembly. The combustion of the fuel stream(s)may produce one or more heated exhaust streams 284. The heated exhauststream(s) may heat, for example, hydrogen-producing region 256, such asto at least a minimum hydrogen-producing temperature. Additionally, theheated exhaust stream(s) may heat vaporization region 276, such as to atleast a minimum vaporization temperature.

Exhaust management assembly 260 may include any suitable structureconfigured to manage exhaust streams in enclosure 254, such as heatedexhaust streams 284. For example, the exhaust management assembly mayinclude a sensor assembly 286, a damper assembly 288, and a controlassembly 290, as shown in FIG. 9.

Sensor assembly 286 may include any suitable structure configured todetect and/or measure one or more suitable operating variables and/orparameters in the hydrogen generation assembly and/or generate one ormore signals based on the detected and/or measured operating variable(s)and/or parameter(s). For example, the sensor assembly may detect mass,volume, flow, temperature, electrical current, pressure, refractiveindex, thermal conductivity, density, viscosity, optical absorbance,electrical conductivity, and/or other suitable variable(s), and/orparameter(s). In some embodiments, the sensor assembly may detect one ormore triggering events.

For example, sensor assembly 286 may include one or more sensors 292configured to detect pressure, temperature, flowrate, volume, and/orother parameters in any suitable portion(s) of the hydrogen generationassembly. Sensors 292 may, for example, include at least onehydrogen-producing region sensor 294 configured to detect one or moresuitable operating variables, parameters, and/or triggering events inhydrogen-producing region 256. The hydrogen-producing region sensor maybe configured to detect, for example, temperature in thehydrogen-producing region and/or generate one or more signals based onthe detected temperature in the hydrogen-producing region.

Additionally, sensors 292 may include at least one purification regionsensor 296 configured to detect one or more suitable operatingvariables, parameters, and/or triggering events in purification region268. The purification region sensor may be configured to detect, forexample, temperature in the purification region and/or generate one ormore signals based on the detected temperature in the purificationregion.

Damper assembly 288 may include any suitable structure configured tomanage flow, such as the flow of exhaust gases (or heated exhauststream(s) 284), through exhaust port 262. For example, damper assembly288 may include at least one damper 298 and at least one actuator 300.The damper may be moveably connected to exhaust port 262. For example,damper 298 may be slidably, pivotably, and/or rotatably connected to theexhaust port.

Additionally, the damper may be configured to move among a plurality ofpositions. Those positions may include, for example, a fully openposition 302, a closed position 304, and a plurality of intermediateopen positions 306 between the fully open and closed positions, as shownin FIGS. 10-12. In the fully open position, damper 298 may allow one ormore exhaust streams 307 (such as heated exhaust stream(s) 284 and/orother exhaust gases in the enclosure) to flow through exhaust port 262.In the closed position, damper 298 may block the exhaust port andprevent exhaust stream(s) from flowing through the exhaust port. Theintermediate open positions may allow the exhaust stream(s) to flowthrough exhaust port 262 at slower rate(s) than when the damper is inthe fully open position. During operation, the temperature in thehydrogen-producing region may decrease when the exhaust stream(s) arerestricted by the damper.

Damper 298 may include any suitable structure. For example, damper 298may be a gate-type damper with one or more plates that slide across theexhaust port, such as shown in FIGS. 10-12. Additionally, damper 298 maybe a flapper-type damper, such as shown in FIG. 9. The flapper-typedamper may, for example, include full circle or half-circle inserts thatpivot to open or close the exhaust. Actuator 300 may include anysuitable structure configured to move damper 298 among the plurality ofpositions. In some embodiments, the actuator may move the damperincrementally between the fully open and closed positions. Althoughdamper assembly 288 is shown to include a single damper and a singleactuator, the damper assembly may include two or more dampers and/or twoor more actuators.

Control assembly 290 may include any suitable structure configured tocontrol damper assembly 288 based, at least in part, on input(s) fromsensor assembly 286, such as based, at least in part, on detected and/ormeasured operating variable(s) and/or parameter(s) by the sensorassembly. Control assembly 290 may receive input(s) only from sensorassembly 286 or the control assembly may receive input(s) from othersensor assemblies of the hydrogen generation assembly. Control assembly290 may control only damper assembly, or the control assembly maycontrol one or more other components of the hydrogen generationassembly.

Control assembly 290 may, for example, be configured to move damper 298,such as via actuator 300, between the fully open and closed positionsbased, at least in part, on the detected temperature in thehydrogen-producing region and/or the purification region. When controlassembly 290 receives inputs from two or more sensors, the controlassembly may select the input with a higher value, may select the inputwith a lower value, may calculate an average of the input values, maycalculate a median of the input values, and/or perform other suitablecalculation(s). For example, control assembly 290 may be configured tomove the damper toward (or incrementally toward) the closed positionwhen detected temperature in the hydrogen-producing and/or purificationregions are above a predetermined maximum temperature, and/or to movethe damper toward (or incrementally toward) the fully open position whenthe detected temperature in the hydrogen-producing and/or purificationregions are below a predetermined minimum temperature. The predeterminedmaximum and minimum temperatures may be any suitable maximum and minimumtemperatures. For example, the maximum and minimum temperatures may beset based on a desired range of temperatures for operating thevaporization, hydrogen-producing, and/or purification regions.

Another example of hydrogen generation assembly 20 is generallyindicated at 308 in FIG. 13. Unless specifically excluded, hydrogengeneration assembly 308 may include one or more components of one ormore other hydrogen generation assemblies described in this disclosure.The hydrogen generation assembly may provide or supply hydrogen to oneor more hydrogen consuming devices 310, such as a fuel cell, hydrogenfurnace, etc. Hydrogen generation assembly 308 may, for example, includea fuel processing assembly 312 and a product hydrogen management system314.

Fuel processing assembly 312 may include any suitable structureconfigured to generate one or more product hydrogen streams 316 (such asone or more hydrogen gas streams) from one or more feed streams 318 viaone or more suitable mechanisms, such as steam reforming, autothermalreforming, electrolysis, thermolysis, partial oxidation, plasmareforming, photocatalytic water splitting, sulfur-iodine cycle, etc. Forexample, fuel processing assembly 312 may include one or more hydrogengenerator reactors 320, such as reformer(s), electrolyzer(s), etc. Feedstream(s) 318 may be delivered to the fuel processing assembly via oneor more feed conduits 317 from one or more feedstock delivery systems(not shown).

Fuel processing assembly 312 may be configured to be operable among aplurality of modes, such as a run mode and a standby mode. In the runmode, the fuel processing assembly may produce or generate the producthydrogen stream(s) from the feed stream(s). For example, in the runmode, the feedstock delivery system may deliver the feed stream to thefuel processing assembly and/or may perform other operation(s).Additionally, in the run mode, the fuel processing assembly may receivethe feed stream, may combust the fuel stream via the heating assembly,may vaporize the feed stream via the vaporization region, may generatethe output stream via the hydrogen producing region, may generate theproduct hydrogen stream and the byproduct stream via the purificationregion, and/or may perform other operations.

In the standby mode, fuel processing assembly 312 may not produce theproduct hydrogen stream(s) from the feed stream(s). For example, in thestandby mode, the feedstock delivery system may not deliver the feedstream to the fuel processing assembly and/or may not perform otheroperation(s). Additionally, in the standby mode, the fuel processingassembly may not receive the feed stream, may not combust the fuelstream via the heating assembly, may not vaporize the feed stream viathe vaporization region, may not generate the output stream via thehydrogen producing region, may not generate the product hydrogen streamand the byproduct stream via the purification region, and/or may notperform other operations. The standby mode may include when the fuelprocessing assembly is powered down or when there is no power to thefuel processing assembly.

In some embodiments, the plurality of modes may include one or morereduced output modes. For example, fuel processing assembly 312 mayproduce or generate product hydrogen stream(s) 316 at a first outputrate when in the run mode (such as at a maximum output rate or normaloutput rate), and produce or generate the product hydrogen stream(s) atsecond, third, fourth, or more rates that are lower (or higher) than thefirst rate when in the reduced output mode (such as at a minimum outputrate).

Product hydrogen management system 314 may include any suitablestructure configured to manage product hydrogen generated by fuelprocessing assembly 312. Additionally, the product hydrogen managementsystem may include any suitable structure configured to interact withfuel processing assembly 312 to maintain any suitable amount of producthydrogen available for hydrogen consuming device(s) 310. For example,product hydrogen management system 314 may include a product conduit322, a buffer tank 324, a buffer tank conduit 325, a sensor assembly326, and a control assembly 328.

Product conduit 322 may be configured to fluidly connect fuel processingassembly 312 with buffer tank 324. Buffer tank 324 may be configured toreceive product hydrogen stream 316 via product conduit 322, to retain apredetermined amount or volume of the product hydrogen stream, and/or toprovide the product hydrogen stream to one or more hydrogen consumingdevices 310. In some embodiments, the buffer tank may be alower-pressure buffer tank. The buffer tank may be any suitable sizebased on one or more factors, such as expected or actual hydrogenconsumption by the hydrogen consuming device(s), cycling characteristicsof the hydrogen generator reactor, fuel processing assembly, etc.

In some embodiments, buffer tank 324 may be sized to provide enoughhydrogen for a minimum amount of time of operation of the hydrogenconsuming device(s) and/or for a minimum amount of time of operation forthe fuel processing assembly, such as a minimum amount of time ofoperation for the vaporization region, hydrogen-producing region, and/orpurification region. For example, the buffer tank may be sized for two,five, ten, or more minutes of operation of the fuel processing assembly.Buffer tank conduit 325 may be configured to fluidly connect buffer tank324 with hydrogen consuming device(s) 310.

Sensor assembly 326 may include any suitable structure configured todetect and/or measure one or more suitable operating variables and/orparameters in the buffer tank and/or generate one or more signals basedon the detected and/or measured operating variable(s) and/orparameter(s). For example, the sensor assembly may detect mass, volume,flow, temperature, electrical current, pressure, refractive index,thermal conductivity, density, viscosity, optical absorbance, electricalconductivity, and/or other suitable variable(s), and/or parameter(s). Insome embodiments, the sensor assembly may detect one or more triggeringevents.

For example, sensor assembly 326 may include one or more sensors 330configured to detect pressure, temperature, flowrate, volume, and/orother parameters. Sensors 330 may, for example, include at least onebuffer tank sensor 332 configured to detect one or more suitableoperating variables, parameters, and/or triggering events in the buffertank. The buffer tank sensor may be configured to detect, for example,pressure in the buffer tank and/or generate one or more signals based onthe detected pressure. For example, unless product hydrogen is beingwithdrawn from the buffer tank at a flow rate that is equal to, orgreater than, the incoming flow rate into the buffer tank, the pressureof the buffer tank may increase and the tank sensor may detect theincrease of pressure in the buffer tank.

Control assembly 328 may include any suitable structure configured tocontrol fuel processing assembly 312 based, at least in part, oninput(s) from sensor assembly 326, such as based, at least in part, ondetected and/or measured operating variable(s) and/or parameter(s) bythe sensor assembly. Control assembly 328 may receive input(s) only fromsensor assembly 326 or the control assembly may receive input(s) fromother sensor assemblies of the hydrogen generation assembly. Controlassembly 328 may control only the fuel processing assembly, or thecontrol assembly may control one or more other components of thehydrogen generation assembly. The control assembly may communicate withthe sensor assembly, the fuel processing assembly, and/or a productvalve assembly (further described below) via communication linkages 333.Communication linkages 333 may be any suitable wired and/or wirelessmechanism for one- or two-way communication between the correspondingdevices, such as input signals, command signals, measured parameters,etc.

Control assembly 328 may, for example, be configured to operate fuelprocessing assembly 312 between the run and standby modes based, atleast in part, on the detected pressure in buffer tank 324. For example,control assembly 328 may be configured to operate the fuel processingassembly in the standby mode when the detected pressure in the buffertank is above a predetermined maximum pressure, and/or to operate thefuel processing assembly in the run mode when the detected pressure inthe buffer tank is below a predetermined minimum pressure.

The predetermined maximum and minimum pressures may be any suitablemaximum and minimum pressures. Those predetermined pressures may beindependently set, or set without regard to other predeterminedpressure(s) and/or other predetermined variable(s). For example, thepredetermined maximum pressure may be set based on the operatingpressure range of the fuel processing assembly, such as to preventoverpressure in the fuel processing assembly because of back pressurefrom the product hydrogen management system. Additionally, thepredetermined minimum pressure may be set based on the pressure requiredby the hydrogen consuming device(s). Alternatively, control assembly 328may operate the fuel processing assembly to operate in the run modewithin a predetermined range of pressure differentials (such as betweenthe fuel processing assembly and the buffer tank and/or between thebuffer tank and the hydrogen consuming device(s)), and in the standbymode when outside the predetermined range of pressure differentials.

In some embodiments, product hydrogen management system 314 may includea product valve assembly 334, which may include any suitable structureconfigured to manage and/or direct flow in product conduit 322. Forexample, the product valve assembly may allow the product hydrogenstream to flow from the fuel processing assembly to the buffer tank, asindicated at 335. Additionally, product valve assembly 334 may beconfigured to vent product hydrogen stream 316 from fuel processingassembly 312, as indicated at 337. The vented product hydrogen streammay be discharged to atmosphere and/or to a vented product hydrogenmanagement system (not shown).

Product valve assembly 334 may, for example, include one or more valves336 that are configured to operate between a flow position in which theproduct hydrogen stream from the fuel processing assembly flows throughthe product conduit and into the buffer tank, and a vent position inwhich the product hydrogen stream from the fuel processing assembly isvented. Valve(s) 336 may be positioned along any suitable portion(s) ofthe product conduit prior to the buffer tank.

Control assembly 328 may be configured to operate the product valveassembly based on, for example, input(s) from sensor assembly. Forexample, the control assembly may direct or control the product valveassembly (and/or valve(s) 336) to vent the product hydrogen stream fromthe fuel processing assembly when the fuel processing assembly is in thestandby mode. Additionally, control assembly 328 may direct or controlproduct valve assembly 334 (and/or valve(s) 336) to allow the producthydrogen stream to flow from the fuel processing assembly to the buffertank when fuel processing assembly 312 is in the run mode and/or reducedoutput mode(s).

Another example of hydrogen generation assembly 20 is generallyindicated at 338 in FIG. 14. Unless specifically excluded, hydrogengeneration assembly 338 may include one or more components of one ormore other hydrogen generation assemblies described in this disclosure.The hydrogen generation assembly may provide or supply hydrogen to oneor more hydrogen consuming devices 340, such as a fuel cell, hydrogenfurnace, etc. Hydrogen generation assembly 338 may, for example, includea fuel processing assembly 342 and a product hydrogen management system344. Fuel processing assembly 342 may include any suitable structureconfigured to generate one or more product hydrogen streams 346 (such asone or more hydrogen gas streams) from one or more feed streams 348 viaone or more suitable mechanisms.

Product hydrogen management system 344 may include any suitablestructure configured to manage product hydrogen generated by fuelprocessing assembly 342. Additionally, the product hydrogen managementsystem may include any suitable structure configured to interact withfuel processing assembly 342 to maintain any suitable amount of producthydrogen available for hydrogen consuming device(s) 340. For example,product hydrogen management system 344 may include a product conduit349, a buffer tank 352, a buffer tank conduit 353, a buffer tank sensorassembly 354, a product valve assembly 355, and a control assembly 356.

Product conduit 349 may be configured to fluidly connect fuel processingassembly 342 with buffer tank 352. The product conduit may include anysuitable number of valves, such as check valve(s) (such as check valve350), control valve(s), and/or other suitable valves. Check valve 350may prevent backflow from the buffer tank toward the fuel processingassembly. The check valve may open at any suitable pressures, such as 1psi or less. Buffer tank 352 may be configured to receive producthydrogen stream 346 via product conduit 349, to retain a predeterminedamount or volume of the product hydrogen stream, and/or to provide theproduct hydrogen stream to one or more hydrogen consuming devices 340.

Buffer tank conduit 353 may be configured to fluidly connect buffer tank352 and hydrogen consuming device(s) 340. The buffer tank conduit mayinclude any suitable number of valves, such as check valve(s), controlvalve(s), and/or other suitable valve(s). For example, the buffer tankconduit may include one or more control valves 351. Control valve 351may allow isolation of the buffer tank and/or other components of thehydrogen generation assembly. The control valve may, for example, becontrolled by control assembly 356 and/or other control assembly(ies).

Tank sensor assembly 354 may include any suitable structure configuredto detect and/or measure one or more suitable operating variables and/orparameters in the buffer tank and/or generate one or more signals basedon the detected and/or measured operating variable(s) and/orparameter(s). For example, the buffer tank sensor assembly may detectmass, volume, flow, temperature, electrical current, pressure,refractive index, thermal conductivity, density, viscosity, opticalabsorbance, electrical conductivity, and/or other suitable variable(s),and/or parameter(s). In some embodiments, the buffer tank sensorassembly may detect one or more triggering events. For example, buffertank sensor assembly 354 may include one or more tank sensors 358configured to detect pressure, temperature, flowrate, volume, and/orother parameters. Buffer tank sensors 358 may, for example, beconfigured to detect pressure in the buffer tank and/or generate one ormore signals based on the detected pressure.

Product valve assembly 355 may include any suitable structure configuredto manage and/or direct flow in product conduit 349. For example, theproduct valve assembly may allow the product hydrogen stream to flowfrom the fuel processing assembly to the buffer tank, as indicated at359. Additionally, product valve assembly 355 may be configured to ventproduct hydrogen stream 346 from fuel processing assembly 342, asindicated at 361. The vented product hydrogen stream may be dischargedto atmosphere and/or to a vented product hydrogen management system (notshown) including discharging vented product hydrogen back to the fuelprocessing assembly.

Product valve assembly 355 may, for example, include a three-waysolenoid valve 360. The three-way solenoid valve may include a solenoid362 and a three-way valve 364. The three-way valve may be configured tomove between a plurality of positions. For example, three-way valve 364may be configured to move between a flow position 363 and a ventposition 365, as shown in FIGS. 15-16. In the flow position, the producthydrogen stream is allowed to flow from the fuel processing assembly tothe buffer tank, as indicated at 359. In the vent position, the producthydrogen stream from the fuel processing assembly is vented, asindicated at 361. Additionally, the three-way valve may be configured toisolate the buffer tank from the product hydrogen stream when the valveis in the vent position. Solenoid 362 may be configured to move valve364 between the flow and vent positions based on input(s) received fromcontrol assembly 356 and/or other control assembly(ies).

Control assembly 356 may include any suitable structure configured tocontrol fuel processing assembly 342 and/or product valve assembly 355based, at least in part, on input(s) from buffer tank sensor assembly354, such as based, at least in part, on detected and/or measuredoperating variable(s) and/or parameter(s) by the buffer tank sensorassembly. Control assembly 356 may receive input(s) only from buffertank sensor assembly 354 and/or the control assembly may receiveinput(s) from other sensor assemblies of the hydrogen generationassembly. Additionally, control assembly 356 may control only the fuelprocessing assembly, only the product valve assembly, only both the fuelprocessing assembly and the product valve assembly, or the fuelprocessing assembly, product valve assembly and/or one or more othercomponents of the hydrogen generation assembly. Control assembly 356 maycommunicate with the fuel processing assembly, the buffer tank sensorassembly, and the product valve assembly via communication linkages 357.Communication linkages 357 may be any suitable wired and/or wirelessmechanism for one- or two-way communication between the correspondingdevices, such as input signals, command signals, measured parameters,etc.

Control assembly 356 may, for example, be configured to operate fuelprocessing assembly 342 among or between the run and standby modes(and/or reduced output mode(s)) based, at least in part, on the detectedpressure in buffer tank 352. For example, control assembly 356 may beconfigured to operate the fuel processing assembly in the standby modewhen the detected pressure in the buffer tank is above a predeterminedmaximum pressure, to operate the fuel processing assembly in one or morereduced output mode(s) when the detected pressure in the buffer tank isbelow a predetermined maximum pressure and/or above a predeterminedoperating pressure, and/or to operate the fuel processing assembly inthe run mode when the detected pressure in the buffer tank is below apredetermined operating pressure and/or predetermined minimum pressure.The predetermined maximum and minimum pressures and/or predeterminedoperating pressure(s) may be any suitable pressures. For example, theone or more of the above pressures may be independently set based on adesired range of pressures for the fuel processing assembly, producthydrogen in the buffer tank, and/or the pressure requirements of thehydrogen consuming device(s). Alternatively, control assembly 356 mayoperate the fuel processing assembly to operate in the run mode within apredetermined range of pressure differentials (such as between the fuelprocessing assembly and the buffer tank), and in the reduced outputand/or standby mode when outside the predetermined range of pressuredifferentials.

Additionally, control assembly 356 may be configured to operate theproduct valve assembly based on, for example, input(s) from sensorassembly. For example, the control assembly may direct or controlsolenoid 362 to move three-way valve 364 to the vent position when thefuel processing assembly is in the standby mode. Additionally, controlassembly 356 may direct or control the solenoid to move three-way valve364 to the flow position when fuel processing assembly 342 is in the runmode.

Control assembly 356 may, for example, include a controller 366, aswitching device 368, and a power supply 370. Controller 366 may haveany suitable form, such as a computerized device, software executing ona computer, an embedded processor, programmable logic controller, ananalog device, and/or functionally equivalent devices. Additionally, thecontroller may include any suitable software, hardware, and/or firmware.

Switching device 368 may include any suitable structure configured toallow controller 366 to control solenoid 362. For example, the switchingdevice may include a solid-state relay 372. The solid-state relay mayallow controller 366 to control solenoid 362 via power supply 370. Forexample, when solenoid 362 is controlled with 24 volts, the solid-staterelay may allow controller 366 to use a voltage signal less than 24volts (such as 5 volts) to control solenoid 362. Power supply 370 mayinclude any suitable structure configured to provide power sufficient tocontrol solenoid 362. For example, power supply 370 may include one ormore batteries, one or more solar panels, etc. In some embodiments, thepower supply may include one or more electrical outlet connectors andone or more rectifiers (not shown). Although the solenoid and controllerare described to operate at certain voltages, the solenoid andcontroller may operate at any suitable voltages.

Another example of hydrogen generation assembly 20 is generallyindicated at 374 in FIG. 17. Unless specifically excluded, hydrogengeneration assembly 374 may include one or more components of one ormore other hydrogen generation assemblies described in this disclosure.The hydrogen generation assembly may provide or supply hydrogen to oneor more hydrogen consuming devices 376, such as a fuel cell, hydrogenfurnace, etc. Hydrogen generation assembly 374 may, for example, includea fuel processing assembly 378 and a product hydrogen management system380. Fuel processing assembly 378 may include any suitable structureconfigured to generate one or more product hydrogen streams 382 (such asone or more hydrogen gas streams) from one or more feed streams 384 viaone or more suitable mechanisms.

Product hydrogen management system 380 may include any suitablestructure configured to manage product hydrogen generated by fuelprocessing assembly 382 and/or interact with fuel processing assembly382 to maintain any suitable amount of product hydrogen available forhydrogen consuming device(s) 376. For example, product hydrogenmanagement system 380 may include a product conduit 386, a buffer tank388, a buffer tank conduit 389, a tank sensor assembly 390, a productvalve assembly 392, and a control assembly 394.

Product conduit 386 may be configured to fluidly connect fuel processingassembly 378 with buffer tank 388. The product conduit may include aflow portion or leg 395 and a vent portion or leg 396. Additionally,product conduit 386 may include any suitable number of valves, such ascheck valve(s) (such as check valve 397), control valve(s), and/or othersuitable valve(s). Buffer tank 388 may be configured to receive producthydrogen stream 382 via product conduit 386, to retain predeterminedamount(s) or volume(s) of the product hydrogen stream, and/or to providethe product hydrogen stream to one or more hydrogen consuming devices376.

Buffer tank conduit 389 may be configured to fluidly connect buffer tank388 with hydrogen consuming device(s) 376. The buffer tank conduit mayinclude any suitable number of valves, such as check valve(s), controlvalve(s), and/or other suitable valve(s). For example, the buffer tankconduit may include one or more control valves 398. Control valve 398may allow isolation of the buffer tank and/or other components of thehydrogen generation assembly. The control valve may, for example, becontrolled by control assembly 394 and/or other control assembly(ies).

Tank sensor assembly 390 may include any suitable structure configuredto detect and/or measure one or more suitable operating variables and/orparameters in the buffer tank and/or generate one or more signals basedon the detected and/or measured operating variable(s) and/orparameter(s). For example, the tank sensor assembly may detect mass,volume, flow, temperature, electrical current, pressure, refractiveindex, thermal conductivity, density, viscosity, optical absorbance,electrical conductivity, and/or other suitable variable(s), and/orparameter(s). In some embodiments, the tank sensor assembly may detectone or more triggering events. For example, tank sensor assembly 390 mayinclude one or more tank sensors 400 configured to detect pressure,temperature, flowrate, volume, and/or other parameters. Tank sensors 400may, for example, be configured to detect pressure in the buffer tankand/or generate one or more signals based on the detected pressure.

Product valve assembly 392 may include any suitable structure configuredto manage and/or direct flow in product conduit 386. For example, theproduct valve assembly may allow the product hydrogen stream to flowfrom the fuel processing assembly to the buffer tank (as indicated at401), and/or vent product hydrogen stream 382 from fuel processingassembly 378 (as indicated at 403). The vented product hydrogen streammay be discharged to atmosphere and/or to a vented product hydrogenmanagement system (not shown).

Product valve assembly 392 may, for example, include a first solenoidvalve 402 and a second solenoid valve 404. The first solenoid valve mayinclude a first solenoid 406 and a first valve 408, while the secondsolenoid valve may include a second solenoid 410 and a second valve 412.As shown in FIGS. 18-19, the first valve may be configured to movebetween a plurality of positions, including a first open position 407and a first closed position 409. Additionally, the second valve may beconfigured to move between a plurality of positions, including a secondopen position 411 and a second closed position 413.

When the first valve is in the open position, the product hydrogenstream is allowed to flow from the fuel processing assembly to thebuffer tank. In contrast, when the first valve is in the closedposition, buffer tank is isolated from the product hydrogen stream fromthe fuel processing assembly (or the product hydrogen stream from thefuel processing assembly is not allowed to flow to the buffer tank).When the second valve is in the open position, the product hydrogenstream from the fuel processing assembly is vented. In contrast, whenthe second valve is in the closed position, the product hydrogen streamfrom the fuel processing assembly is not vented.

First solenoid 406 may be configured to move first valve 408 between theopen and closed positions based on input(s) received from controlassembly 394. Additionally, second solenoid 410 may be configured tomove second valve 412 between the open and closed position based oninput(s) received from the control assembly.

Control assembly 394 may include any suitable structure configured tocontrol fuel processing assembly 378 and/or product valve assembly 392based, at least in part, on input(s) from buffer tank sensor assembly390, such as based, at least in part, on detected and/or measuredoperating variable(s) and/or parameter(s) by the buffer tank sensorassembly. Control assembly 394 may receive input(s) only from buffertank sensor assembly 390 and/or the control assembly may receiveinput(s) from other sensor assemblies of the hydrogen generationassembly. Additionally, control assembly 394 may control only the fuelprocessing assembly, only the product valve assembly, only both the fuelprocessing assembly and the product valve assembly, or the fuelprocessing assembly, product valve assembly and/or one or more othercomponents of the hydrogen generation assembly. Control assembly 394 maycommunicate with the fuel processing assembly, the buffer tank sensorassembly, and/or the product valve assembly via communication linkages393. Communication linkages 393 may be any suitable wired and/orwireless mechanism for one- or two-way communication between thecorresponding devices, such as input signals, command signals, measuredparameters, etc.

Control assembly 394 may, for example, be configured to operate fuelprocessing assembly 378 between the run and standby modes (and/orreduced output mode(s)) based, at least in part, on the detectedpressure in buffer tank 388. For example, control assembly 394 may beconfigured to operate the fuel processing assembly in the standby modewhen the detected pressure in the buffer tank is above a predeterminedmaximum pressure, to operate the fuel processing assembly in one or morereduced output mode(s) when the detected pressure in the buffer tank isbelow a predetermined maximum pressure and/or above a predeterminedoperating pressure, and/or to operate the fuel processing assembly inthe run mode when the detected pressure in the buffer tank is below apredetermined operating pressure and/or predetermined minimum pressure.The predetermined maximum and minimum pressures and/or predeterminedoperating pressure(s) may be any suitable pressures. For example, theone or more of the above pressures may be independently set based on adesired range of pressures for the fuel processing assembly, the producthydrogen in the buffer tank, and/or the pressure requirements of thehydrogen consuming device(s). Alternatively, control assembly 394 mayoperate the fuel processing assembly to operate in the run mode within apredetermined range of pressure differentials (such as between the fuelprocessing assembly and the buffer tank and/or between the buffer tankand the hydrogen consuming device(s)), and in the reduced output and/orstandby mode(s) when outside the predetermined range of pressuredifferentials.

Additionally, control assembly 394 may be configured to operate theproduct valve assembly based on, for example, input(s) from sensorassembly. For example, the control assembly may direct or control thefirst and/or second solenoids to move the first valve in the closedposition and/or the second valve in the open position when the fuelprocessing assembly is in the standby mode. Additionally, controlassembly 394 may direct or control the first and/or second solenoids tomove the first valve in the open position and/or the second valve in theclosed position when fuel processing assembly 378 is in the run modeand/or reduced output mode(s).

Control assembly 394 may, for example, include a controller 414, aswitching device 416, and a power supply 418. Controller 414 may haveany suitable form, such as a computerized device, software executing ona computer, an embedded processor, programmable logic controller, ananalog device, and/or functionally equivalent devices. Additionally, thecontroller may include any suitable software, hardware, and/or firmware.

Switching device 416 may include any suitable structure configured toallow controller 414 to control the first and/or second solenoids. Forexample, the switching device may include a solid-state relay 420. Powersupply 418 may include any suitable structure configured to providepower sufficient to control the first and/or second solenoids.

Hydrogen generation assemblies of the present disclosure may include oneor more of the following:

-   -   A feed assembly configured to deliver a feed stream to a fuel        processing assembly.    -   A feed tank configured to contain feedstock for a feed stream.    -   A feed conduit fluidly connecting a feed tank and a fuel        processing assembly.    -   A pump configured to deliver a feed stream at a plurality of        flowrates to a fuel processing assembly via a feed conduit.    -   A feed sensor assembly configured to detect pressure in a feed        conduit downstream from a pump.    -   A feed sensor assembly configured to generate a signal based on        detected pressure.    -   A pump controller configured to select a flowrate from a        plurality of flowrates based on detected pressure.    -   A pump controller configured to operate a pump at a selected        flowrate.    -   A pump controller configured to select a flowrate for a pump        based solely on detected pressure.    -   A pump controller configured to condition a signal received from        a sensor assembly.    -   A pump controller configured to invert a signal received from a        feed sensor assembly.    -   A pump controller configured to select a flowrate based on a        conditioned signal.    -   A pump controller configured to select a flowrate based on an        inverted signal.    -   A fuel processing assembly configured to receive a feed stream.    -   A fuel processing assembly configured to produce a product        hydrogen stream from a feed stream.    -   A fuel processing assembly configured to be operable among a        plurality of modes.    -   A fuel processing assembly configured to be operable among a run        mode in which the fuel processing assembly produces a product        hydrogen stream from a feed stream, and a standby mode in which        the fuel processing assembly does not produce the product        hydrogen stream from the feed stream.    -   A purge assembly.    -   A pressurized gas assembly configured to receive at least one        container of pressurized gas that is configured to purge a fuel        processing assembly.    -   A purge conduit configured to fluidly connect a pressurized gas        assembly and a fuel processing assembly.    -   A purge valve assembly configured to allow at least one        pressurized gas to flow through a purge conduit from a        pressurized gas assembly to a hydrogen generation assembly when        power to the hydrogen generation assembly is interrupted.    -   A solenoid valve that moves between a closed position in which        at least one pressurized gas does not flow through a purge        conduit from a pressurized gas assembly, and an open position in        which the at least one pressurized gas is allowed to flow        through the purge conduit from the pressurized gas assembly.    -   A solenoid valve that is in the closed position when there is        power to a fuel processing assembly.    -   A solenoid valve that automatically moves to an open position        when power to a fuel processing assembly is interrupted.    -   A solenoid valve configured to move to a closed position when        the solenoid valve receives a control signal.    -   A solenoid valve configured to automatically move to an open        position when the solenoid valve does not receive a control        signal.    -   A control system configured to send a control signal to a        solenoid valve.    -   An enclosure containing at least a portion of a fuel processing        assembly and at least a portion of a purge assembly.    -   An enclosure having an exhaust port.    -   A hydrogen-producing region contained within an enclosure.    -   A hydrogen-producing region configured to produce, via a steam        reforming reaction, a reformate stream from at least one feed        stream.    -   A purification region contained within an enclosure.    -   A purification region including a hydrogen-selective membrane.    -   A purification region configured to produce a permeate stream        comprised of the portion of a reformate stream that passes        through a hydrogen-selective membrane, and a byproduct stream        comprised of the portion of the reformate stream that does not        pass through the membrane.    -   A reformer sensor assembly configured to detect temperature        within a hydrogen-producing region.    -   A reformer sensor assembly configured to detect temperature in        the purification region.    -   A heating assembly configured to receive at least one air stream        and at least one fuel stream.    -   A heating assembly configured to combust at least one fuel        stream within a combustion region contained within an enclosure        producing a heated exhaust stream for heating at least a        hydrogen-producing region to at least a minimum        hydrogen-producing temperature.    -   A damper moveably connected to an exhaust port.    -   A damper configured to move among a plurality of positions.    -   A damper configured to move among a fully open position in which        the damper allows a heated exhaust stream to flow through an        exhaust port, a closed position in which the damper prevents the        heated exhaust stream from flowing through the exhaust port, and        a plurality of intermediate open positions between the fully        open and closed positions.    -   A damper controller configured to move a damper between fully        open and closed positions based, at least in part, on a detected        temperature in a hydrogen-producing region.    -   A damper controller configured to move a damper between fully        open and closed positions based, at least in part, on a detected        temperature in at least one of a hydrogen-producing region and a        purification region.    -   A damper controller configured to move a damper toward a closed        position when a detected temperature is above a predetermined        maximum temperature.    -   A damper controller configured to move a damper toward an open        position when a detected temperature is below a predetermined        minimum temperature.    -   A buffer tank configured to contain a product hydrogen stream.    -   A product conduit fluidly connecting a fuel processing assembly        and a buffer tank.    -   A tank sensor assembly configured to detect pressure in a buffer        tank.    -   A product valve assembly configured to manage flow in a product        conduit.    -   At least one valve that is configured to operate between a flow        position in which a product hydrogen stream from a fuel        processing assembly flows through a product conduit and into a        buffer tank, and a vent position in which the product hydrogen        stream from the fuel processing assembly is vented prior to the        buffer tank.    -   A three-way solenoid valve.    -   A first valve configured to control flow of a product hydrogen        stream between a fuel processing assembly and a buffer tank.    -   A first valve configured to move between a first open position        in which a product hydrogen stream flows between a fuel        processing assembly and a buffer tank, and a first closed        position in which the product hydrogen stream does not flow        between the fuel processing assembly and the buffer tank.    -   A second valve configured to vent a product hydrogen stream from        a fuel processing assembly.    -   A second valve configured to move between a second open position        in which a product hydrogen stream is vented, and a second        closed position in which the product hydrogen stream is not        vented.    -   A control assembly configured to operate a fuel processing        assembly between run and standby modes based, at least in part,        on detected pressure.    -   A control assembly configured to operate a fuel processing        assembly in a standby mode when detected pressure in a buffer        tank is above a predetermined maximum pressure.    -   A control assembly configured to operate a fuel processing        assembly in a run mode when detected pressure in a buffer tank        is below a predetermined minimum pressure.    -   A control assembly configured to direct a product valve assembly        to vent a product hydrogen stream from a fuel processing        assembly when the fuel processing assembly is in the standby        mode.    -   A control assembly configured to move at least one valve to a        flow position when a fuel processing assembly is in a run mode.    -   A control assembly configured to move at least one valve to a        vent position when a fuel processing assembly is in a standby        mode.    -   A control assembly configured to move a first valve to a first        open position and a second valve to a second closed position        when a fuel processing assembly is in a run mode.    -   A control assembly configured to move a first valve to a first        closed position and a second valve to a second open position        when a fuel processing assembly is in a standby mode.

INDUSTRIAL APPLICABILITY

The present disclosure, including hydrogen generation assemblies,hydrogen purification devices, and components of those assemblies anddevices, is applicable to the fuel-processing and other industries inwhich hydrogen gas is purified, produced, and/or utilized.

The disclosure set forth above encompasses multiple distinct inventionswith independent utility. While each of these inventions has beendisclosed in its preferred form, the specific embodiments thereof asdisclosed and illustrated herein are not to be considered in a limitingsense as numerous variations are possible. The subject matter of theinventions includes all novel and non-obvious combinations andsubcombinations of the various elements, features, functions and/orproperties disclosed herein. Similarly, where any claim recites “a” or“a first” element or the equivalent thereof, such claim should beunderstood to include incorporation of one or more such elements,neither requiring nor excluding two or more such elements.

Inventions embodied in various combinations and subcombinations offeatures, functions, elements, and/or properties may be claimed throughpresentation of new claims in a related application. Such new claims,whether they are directed to a different invention or directed to thesame invention, whether different, broader, narrower or equal in scopeto the original claims, are also regarded as included within the subjectmatter of the inventions of the present disclosure.

What is claimed is:
 1. A hydrogen generation assembly, comprising: afuel processing assembly configured to receive a feed stream and producea product hydrogen stream from the feed stream; a feed assemblyconfigured to deliver the feed stream to the fuel processing assembly,the feed assembly including: a feed tank configured to contain feedstockfor the feed stream, a feed conduit fluidly connecting the feed tank andthe fuel processing assembly, and a variable-speed pump configured todeliver the feed stream at a plurality of flowrates to the fuelprocessing assembly via the feed conduit; and a control system,including: a feed sensor assembly configured to detect pressure in thefeed conduit downstream from the pump, and a pump controller configuredto select a flowrate from the plurality of flowrates based on thedetected pressure in the feed conduit, and to operate the pump at theselected flowrate, wherein the feed sensor assembly is furtherconfigured to generate detection signals based on detected pressures inthe feed conduit, and the pump controller is further configured toinvert the detection signals received from the feed sensor assembly andto select flowrates from the plurality of flowrates based on theinverted signals, wherein the detection signals has a first averageslope when the voltages generated by the detection signals areillustrated in a graph against the corresponding detected pressures, andwherein the inverted signals has a second average slope that is thenegative value of the first average slope when the voltages of theinverted signals are illustrated in the graph.
 2. The assembly of claim1, wherein the pump controller is further configured to select theflowrate based solely on the detected pressure in the feed conduit. 3.The assembly of claim 1, further comprising a purge assembly, including:a pressurized gas assembly fluidly connected to the feed conduit andconfigured to receive at least one container of pressurized gas that isconfigured to purge the fuel processing assembly; and a purge valveassembly configured to allow the at least one pressurized gas to flowthrough the feed conduit from the pressurized gas assembly to the fuelprocessing assembly when power to the fuel processing assembly isinterrupted.
 4. The assembly of claim 1, further comprising an enclosurehaving an exhaust port, the fuel processing assembly including ahydrogen-producing region contained within the enclosure and configuredto provide, via a steam reforming reaction, the product hydrogen streamfrom the feed stream, wherein the control system further includes areformer sensor assembly configured to detect temperature in thehydrogen-producing region.
 5. The assembly of claim 4, furthercomprising: a heating assembly configured to receive at least one airstream and at least one fuel stream and to combust the at least one fuelstream within a combustion region contained within the enclosureproducing a heated exhaust stream for heating at least thehydrogen-producing region to at least a minimum hydrogen-producingtemperature; and a damper moveably connected to the exhaust port andconfigured to move among a plurality of positions including a fully openposition in which the damper allows the heated exhaust stream to flowthrough the exhaust port, a closed position in which the damper preventsthe heated exhaust stream from flowing through the exhaust port, and aplurality of intermediate open positions between the fully open andclosed positions, and wherein the control system further includes adamper controller configured to move the damper between the fully openand closed positions based, at least in part, on the detectedtemperature in the hydrogen-producing region.
 6. The assembly of claim1, wherein the fuel processing assembly is further configured to beoperable among a plurality of modes, including a run mode in which thefuel processing assembly produces the product hydrogen stream from thefeed stream, and a standby mode in which the fuel processing assemblydoes not produce the product hydrogen stream from the feed stream. 7.The assembly of claim 6, further comprising a buffer tank configured tocontain the product hydrogen stream, and a product conduit fluidlyconnecting the fuel processing assembly and the buffer tank, wherein thecontrol system further includes: a product sensor assembly configured todetect pressure in the buffer tank, and a control assembly configured tooperate the fuel processing assembly between the run and standby modesbased, at least in part, on the detected pressure in the buffer tank. 8.The assembly of claim 1, wherein the pump controller is configured toonly invert the detection signals received from the feed sensor assemblywithout additional processing of those signals.
 9. The assembly of claim8, wherein the pump controller does not generate signals different fromthe inverted signals to select the flowrates from the plurality offlowrates.
 10. The assembly of claim 1, wherein the feed sensor assemblydoes not detect a triggering event in which pressure in the feed conduitdownstream from the pump reaches or exceeds a predetermined pressure.